首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   733534篇
  免费   51535篇
  国内免费   3537篇
耳鼻咽喉   9365篇
儿科学   23562篇
妇产科学   17915篇
基础医学   113986篇
口腔科学   20423篇
临床医学   67569篇
内科学   138732篇
皮肤病学   16404篇
神经病学   50848篇
特种医学   26726篇
外国民族医学   97篇
外科学   107348篇
综合类   19201篇
现状与发展   11篇
一般理论   164篇
预防医学   53081篇
眼科学   17032篇
药学   56747篇
  34篇
中国医学   3834篇
肿瘤学   45527篇
  2021年   7044篇
  2019年   6390篇
  2018年   8903篇
  2017年   7004篇
  2016年   7672篇
  2015年   8897篇
  2014年   11932篇
  2013年   16687篇
  2012年   22466篇
  2011年   23703篇
  2010年   14061篇
  2009年   12988篇
  2008年   21360篇
  2007年   22943篇
  2006年   23267篇
  2005年   21930篇
  2004年   20858篇
  2003年   19720篇
  2002年   19182篇
  2001年   36918篇
  2000年   37482篇
  1999年   31042篇
  1998年   8384篇
  1997年   7125篇
  1996年   7356篇
  1995年   6978篇
  1994年   6375篇
  1992年   23178篇
  1991年   23087篇
  1990年   22450篇
  1989年   22207篇
  1988年   20185篇
  1987年   19514篇
  1986年   18563篇
  1985年   17372篇
  1984年   12734篇
  1983年   10773篇
  1982年   5949篇
  1979年   11535篇
  1978年   8133篇
  1977年   6834篇
  1976年   6595篇
  1975年   7271篇
  1974年   8499篇
  1973年   8143篇
  1972年   7658篇
  1971年   7130篇
  1970年   6877篇
  1969年   6308篇
  1968年   5782篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Bromocriptine (0.5 mg/kg) and apomorphine (0.03 mg/kg) exert moderate aphrodisiac effect in sexually sluggish rats. This effect appears rapidly and reaches its peak within 24 h. Amphetamine (2 mg/kg) acts similarly but with a more rapid onset and offset of the effect. A single dose of (-)deprenyl, a selective inhibitor of MAO-B, exerts a much more potent effect in this test.  相似文献   
93.
94.
We review evidence suggesting that deaf speakers do not move their articulators toward the following open posture throughout closure and report results from a preliminary cinefluorographic study. Two prelingually deaf and two hearing speakers produced two different strings of alternating heterogeneous monosyllables as though speaking in time with a metronome (the so-called P-center task). Events traditionally associated with vowel production appeared evenly timed throughout the productions, and, in general, the deaf speakers performed similarly to the hearing speakers. We relate the results to Fowler's (1983) interpretation of the P-center phenomenon as an indicant of continuous vowel production.  相似文献   
95.
Biopsies from the diseased bones of patients with familial expansile osteolysis (FEO) were examined by light and electron microscopy. Focal concentrations of multinuclear osteoclasts were present, and these contained viral-like microcylindrical inclusions which appeared exclusive to their nuclei. No consistent relationship was found between osteoclast size and the number of osteoclast nuclei containing microcylindrical inclusions. Quantitative histomorphometry showed evidence of increased bone remodelling with high bone cell densities and a decrease of the reversal period in bone remodelling. The lesions contained prominent woven bone and fibrovascular tissue, together with mononuclear cells and adipocytes. Little bone was found in the most radiolucent lesions, which were almost totally occupied by adipocytes and fibrovascular tissue. Serology did not reveal any significant differences between the viral antibody titres of patients and their age- and sex-matched controls. The present study suggests that intranuclear viral-like microcylindrical inclusions of osteoclasts are not a specific feature of Paget's disease, and are found in other disorders of osteoclast function, including pycnodysostosis, osteopetrosis, giant cell tumours, and familial expansile osteolysis.  相似文献   
96.
A tracer kinetic procedure was developed for the measurement of monoamine oxidase type B (MAO-B) activity using L-[11C]deprenyl and positron emission tomography (PET). The kinetic model consisted of two tissue compartments with irreversible binding to the second compartment (three rate constants). In addition, a blood volume component was included. Special attention was given to the accurate measurement of the plasma and whole blood input functions. The method was applied to the measurement of the dose-response curve of a reversible MAO-B inhibitor (Ro 19-6327). From the results, it followed that the rate constant for irreversible binding (k3) appeared to be a better index of MAO-B activity than the net influx constant Ki. Furthermore, regional analysis demonstrated that Ki, but not k3, was flow dependent. This implies that full kinetic analysis is required for an accurate assessment of MAO-B activity.  相似文献   
97.
The expression of two heat shock proteins, HSP72 and p57, in addition to ubiquitin, has been studied immunocytochemically in nine amyotrophic lateral sclerosis (ALS) cases and 10 age-matched controls. HSP72 and p57 antibodies did not identify the characteristic ubiquitin-immunoreactive inclusions present in anterior horn cells in ALS spinal cord. Antibodies to HSP72, but not to p57 or ubiquitin, strongly labelled structures corresponding to polyglucosan bodies in spinal grey matter. Such immunoreactive profiles were more abundant in ALS cases, although they were also present in control material. They were sometimes identified by haematoxylin and eosin and periodic acid Schiff reaction, but were not labeled by phosphotungstic acid haematoxylin or by antibodies to glial fibrillary acidic protein. Although ubiquitin, HSP72 and p57 are stress-induced proteins, they are expressed differently and might therefore have different significance in neuronal degeneration.  相似文献   
98.
Bronchoalveolar lavage fluid neutrophils were studied by the cytologic methods in 58 patients with chronic bronchitis, 63 ones with bronchiectasis, and 8 normal controls. The study included cytospectrophotometry of myeloperoxidase and alkaline phosphatase activity and estimation of active oxygen-producing cells in the NBT test. Neutrophilic functional activity was different in the patients with chronic bronchitis and bronchiectasis. Neutrophilic myeloperoxidase and alkaline phosphatase activities were lower in the patients with chronic bronchitis than in those with bronchiectasis, whereas the counts of cells active in the NBT test were low in both patient populations.  相似文献   
99.
Sebum excretion rate was measured by a photometric technique. We demonstrated a high correlation between sebum excretion rates on the left and right sides of the upper back and between back and forehead skin. Sebum excretion rate measurements overlying an open comedone (blackhead) were significantly lower than those obtained from normal skin. This observation demonstrates a functional obstruction to the outflow of sebum and would suggest that the lack of involvement of open comedones in inflammatory acne is not because of the maintenance of a free flow of sebum.  相似文献   
100.
A 65-year-old man with spontaneous rupture of the esophagus survived with a direct suture of the esophagus 15 hours after the onset of symptoms. Endoscopic examination of the esophagus was especially of great help in determining the surgical procedure in this patient, and we want to stress the importance of prompt diagnosis and immediate surgery for this disease.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号